No wonder you commented on my wheels haha. Nice.

 

counterweights for certain, e-shaft no

 

curious why you are going with some of the highest compression rotors next to the Rx-8? But then rather ineffective tuning methods.

 

Care to elaborate? I'm new to rotaries any advice you can give me would be appreciated!

 

Non turbo rotors (high compression) for a turbo build (low compression). Mazda engineered low compression TII rotors specifically for the 4 port TII engine.

NA rotors in a TII engine is equivalent to high compression ppp...pistons () installed in a factor turbo charged banger motor instead of the factory low compression "P" words .

With high compression rotors, you will have to detune your engine I order to avoid detonation and run a low boost setting. Some high compression boosted engines require a lower octane (hotter burn) gas to be used as well.

Nice rims. What are the specs?

 

Will I not be able to achieve the same power as with S4 TII rotors?

 

With proper and a lot of tuning. I've heard of privateer RE builders using REW rotors instead of TII rotors.

It would be better to stick with a set of TII rotors to keep your build simple and cost effective. I have seen 6port turbo engine builds on other forums though, so I advise researching threads and forums specifically related to your build preferences. Anything is possible with proper building and tuning. I am not a professional engine builder, so do not take my advise as an only source. Call Mazdatrix and Racing Beat, they have been in the RX7 business since the late 1970's.

 

Did you decide to get your motor back and rebuild yourself? If so have you decided on what rebuild kit ro buy and from where? I was about to tear down my t2 and was wondering about rebuild kits myself.

 

You appear to not understand the nature of an engine. The reason lower compression rotors are preferred in a turbo application is the result of adiabatic efficiency. Essentially, a turbo is a much more efficient compressor of air than the engine itself is. What do I mean by this? Well, let's take an example:

Say you insert 20psi of air into an engine at a 1.0 compression ratio. This nets you 20psi of chamber pressure.

Now, say you insert that same 20psi into a 2.0 compression ratio. 40psi of chamber pressure.

So, if all things were created equal, a high compression setup would be no different than a low compression setup assuming the chamber pressures were the same. The problem is, compression generates heat. With the turbo, you have plenty of opportunity to cool this heat through the intake itself, intercoolers, etc. Once it hits the engine, you're stuck with what you get. This is why they run lower compression in the engine typically, because you have more ability to improve your overall chamber temperatures. However, there are certainly benefits of high compression. High power on lower overall boost, faster spool, etc. It's of course a trade-off. You do not have to "detune" anything. You simply tune for what you have like any other car. Sure, you won't run the same PSI vs PSI of a low compression engine, but why would you? You will make more power on less PSI, so the comparison breaks down.

In any event, a high compression motor requires HIGHER octane ratings to RESIST premature detonation as a result of its higher chamber pressures which create higher chamber temperatures.

With the targets in mind, high compression rotors shouldn't be any need for concern at all -- especially if you incorporate the HIGHLY suggested auxiliary injection system as a FAIL SAFE (what i mean is, tune the car safely WITHOUT it, and then turn the system on as an extra safety buffer). Every RX7 should have auxiliary injection of some kind... there's just no good reason not to!

 

I can substitute auxiliary injection with the use of E85 fuel, correct? Since E85 burns much cooler than traditional gasoline. Also I did some research about the higher compression in turbo applications here's what I've gathered from those who have ran with high compression rotors: The main reason people run lower comp rotors is because it yields a safety factor, all else remaining the same, when running heavy loads. But, the dirty little secret to this has to do with the volatility of the fuel that's being used. Use a fuel that's designed for heavier loads (slower burn rate, higher auto-ignition temperature, colder combustion temperature) then you can use a higher compression ratio.

There is a substantial enough difference with the 1/2pt increase in compression ratio.

-From the wise BDC

 

Yes, although E85 isn't as easily available and will require a fuel system overhaul (bigger pump/injectors than standard fuel counterparts), and of course lacks the benefits of a water mixture injection. Still good stuff, though!

 

Subbing to this thread. Very curious to see what eventually happens. I just went from a Miata to an S4 TII as well. :P

 

Thank you for the clarifications, I thought I knew a little something but apparently I don't . Back to the books to learn.

Sorry for the misinformation Agrovain .

 

lol, don't worry, we all have learning to do about something.

 

 

 

Massive turbo lag upgrade

 

Is that a John Deere logo on the compressor housing?

 

Yes, turbo info: "This is the largest, most efficient and highest power T4 twinscroll turbocharger available in a midsize frame with a 4" inlet compressor housing. It uses a 7-blade Extended Tip compressor wheel w/ 66mm inducer & 91mm exducer rated at 82lb/min. 4" Ported shroud Inlet, 3" outlet compressor housing. Turbine side is a 79mm inconel turbine wheel on a 4340 steel shaft. It uses a .91 A/R T4 twinscroll turbine housing"

 

Has anyone ran that turbo before on the 13b?

 

Haven't looked into it, also i'm going to be using S4 NA rotors in the build instead of the S5 rotors. Aaron Cake gave me some really good advice on boosting NA rotors: "I would HIGHLY suggest not using S5 NA rotors due to the high compression. If you are going to go high compression, use S4 NA rotors which are also far stronger. Then you can just burn high octane pump gas as long as you run conservative AFRs (in the high 10s/low 11s) and conservative timing (I drop timing to 10 degrees after a few PSI). My FC puts out over 500 RWHP using a GT4088R on an S4 NA 6 port engine, bridgeported but all stock block aside from that and 3 window bearings."

 

Paid for my rebuild 5/22/2013 and got it back just now 7/10/2013. So if you want a rebuild and don't care how long it takes to get finished then I strongly recommend Evil Genius Racing lol....

Here's some pictures of the blown rotors and the old housing that was replaced plus some other pics:

 

 

Wow! $1000 just for rebuild labor? What comes with that service?

 

Well that's about right for a rebuild since kits alone are 1k or so and the 1k labor is usually for overhead for a warranty